Recently, as multimedia content such as voice and video expands and prevails, precise multimedia search technology is demanded. With regard to voice search, there is ongoing research about voice search technology that identifies a location within voice where the voice corresponding to a given search word is spoken. With voice search, because of characteristic issues such as the difficulty of voice recognition, a search technique with sufficient performance has not been established compared to string search that identifies a location that includes a desired search word within a string. For this reason, various technologies for realizing voice search of sufficient performance are being researched.